question

When you set the DIP switches 2 and 3 are you "storing" the setting with DIP switch 6 after?
So if you set 2=on and 3=off (for default LiFePO4 settings) you need to switch 6 on and then off again to store the setting. Of course the unit needs to be on to be able to store the setting.

It seems like the equalisation mode id set, that is the only way it can output 16V. That would be odd though because this option is disabled by factory default and can only be enabled with the VE.Configure software. What settings did your supplier say that they set?

Yes, I switched 6 on and off again. There is currently a similar post to mine running but also not with a clear resolution yet.

Have you established cause/effect?

Is the MP going overvoltage causing the battery BMS to trip or is the battery imbalanced, the BMS tripping before absorption is reached and then the MP briefly going over-volt because of the sudden removal of the battery from the charging circuit?

Yes. Battery cell imbalance can happen with new, expensive LFP batteries.

What is odd is that most good BMSs don't cut the discharge when over-voltage protection occurs. They just cut the charge.

Lower absorption voltage to 14.2V and re-assess.

As snoobler suggests you could lower the absorption voltage significantly and test. The aim is to make the battery BMS inactive when "fully" charged. The possible cause is the unintended consequence of the BMS providing instability of the terminal voltage of the battery bank causing the MP to shutdown based on what it perceives as excessive DC ripple.